There are several types of child safety gates known in the art: the lazy-tong expansible gate, as illustrated in U.S. Pat. No. 4,523,745A1 and U.S. Pat. No. 4,723,587A1; and gates which are held into place through a wedging, jamming, or pressure action, as illustrated in U.S. Pat. No. 4,492,263A1 and U.S. Pat. No. 3,431,966A1.
Child safety gates are mainly used to prevent small children from entering dangerous places in a home, i.e. staircases, kitchens etc. Thus the safety gates ought to be easily opened by a grown-up person but not by a child.
Apart from the above mentioned gate types, there is known a type of child safety gate which is designed with a gate barrier member made of flexible sheet material which is rolled up on a roll when not in use, and which can be pulled out to close an opening. Such a gate type is illustrated, for example, in WO9400664A1. The roll is preferably mounted vertically along one side of the opening to be closed by the gate. On the other side of the opening to be closed there is mounted a holding means, such as hooks or other locking means, for locking the free end of the sheet material when the sheet has been pulled out to cover the gate opening.
This type of safety gate is provided with rollback means to provide a momentum for winding up the sheet on the roll when not in use. Since openings to be covered by a child safety gate may be of varying sizes (widths), the sheet material is often longer than the width of the widest of common openings. Hence, when the sheet is extracted to fully cover an opening, it may be pulled out even more, since the width of the opening is less than the length of the sheet. The extra length of the sheet material brings the disadvantage that if someone leans against the sheet, he/she might force the sheet to be further pulled out and hence, he/she may gain access to the other side of the opening. This is undesirable and dangerous for a child or a pet.
Current child safety gates provide some sort of means for keeping the sheet material from being extracted further than a desired length.
WO9400664A1 discloses a child safety gate for blocking a passage, particularly for children and pets. The gate can be suspended at one of its side edges and is lockable at its other side edge by means of a child-proof locking device. The gate consists, between its side edges, of a roll-type curtain, which can be rolled around one of the side edges.
U.S. Pat. No. 6,536,502B2 discloses an adjustable width child safety device comprising an adjustable extension limiter, which makes it possible to set a maximum extension length for the sheet material. A disadvantage of the device is that you can only choose the maximum extension length from a multiplicity of selectable positions, which makes it difficult to perfectly adapt the maximum length of the sheet material to the width of an opening. Further, it is cumbersome to use the safety gate in an opening with another width, since the maximum extension has to be manually adjusted.
U.S. Pat. No. 7,178,792B2 discloses an adjustable width child safety device comprising an electrically operable extension lock adapted to prevent extension of the screen from the housing until electrically unlocked. A disadvantage of the safety device is that a person engaging the safety device might forget to activate the lock, thus presenting potential dangers to a child leaning into the gate. Also, the device is dependant on electricity, which could be dangerous if the electricity for some reason does not work and a person activating the lock does not realize that the locking mechanism did not engage properly. If the electricity does not work it may also be difficult to disengage the lock to remove the safety device from the opening, possibly being dangerous in the case of fire.
U.S. Pat. No. 6,907,914B1 discloses a locking device for a baby safety gate. Using the locking device, it is possible to unwind any length of sheet material and then have the locking device prevent further unwinding once a desired length of sheet material has been unwound. The locking device permits one continuous unwinding action, but prevents further unwinding once a rewinding action has begun. A disadvantage of the locking device is that if a person unwinding the sheet material accidentally releases the sheet material so that a rewinding action begins, a person has to unlock the locking device again to make it possible to unwind the sheet material.
U.S. Pat. No. 5,690,317A1 discloses a spring roller-mounted pull-out screen for use as a child safety barrier across a doorway. Further, a control mechanism is provided for preventing the screen from extending when impacted by a child. The roller is locked against rotation in a direction allowing the screen to unwind unless released by a manual push-button. The roller automatically locks after the screen has been extended and slightly released to be slightly rewound onto the roll. The automatic locking mechanism operates by a friction drive, which releases a pawl to spring into engagement with a ratchet wheel when the screen has been pulled out and released. When closing a gate with the above disclosed control mechanism, a person closing the gates often has to coax with the sheet when attaching it in its extended position. Since the above disclosed control mechanism only allows the sheet to be pulled outwards once every time the sheet has been fully wound up, the person coaxing with the sheet often seem himself/herself having accidentally released the sheet slightly before the sheet was securely attached in its extended position. Thus, the control mechanism locks the sheet from further extraction and the person has to unlock the locking device again to make it possible to unwind the sheet material and once again try to securely attach the sheet in its extended position. Another disadvantage with this system is that the locking mechanism creates a disturbing clicking noise when the sheet is rewound onto the roll. This noise is especially disturbing at night-time. Further, a person having disengaged the locking mechanism in order to open the gate might then decide not to open the gate, whereupon the person might forget to reactivate the locking mechanism. This presents a potential danger for children and animals normally stopped by the gate, since the sheet is free to be wound off the roll.
Thus, a locking device for a child safety gate providing:                safe operation,        easy adoption for openings of different width,        easy opening and closing of the gate, and        quiet operation,would be advantageous.        